SNR S2989G-48TX-RPS — настройка и устранение неполадок IGMP и IGMP Snooping [259/553]

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S2989G-24TX Operation Manual

Chapter 5 Multicast Protocol Related Configuration

4-34

5.2.4

IGMP Troubleshooting

In configuring and using IGMP Protocol, IGMP Protocol might not operate normally

caused by physical connection or incorrect configuration. Therefore, user should pay

attention to the following issues:

 Firstly to assure that physical connection is correct;

 Next, to assure the Protocol of Interface and Link protocol is UP (use show

interface command);

 Afterwards, to assure to start a kind of multicast protocol on the interface;

 Multicast Protocol requires RPF Check using unicast routing; therefore the

correctness of unicast routing must be assured beforehand.

5.3

IGMP Snooping

5.3.1

Introduction to IGMP Snooping

IGMP (Internet Group Management Protocol) is a protocol used in IP multicast. IGMP

is used by multicast enabled network device (such as a router) for host membership query,

and by hosts that are joining a multicast group to inform the router to accept packets of a

certain multicast address. All those operations are done through IGMP message

exchange. The router will use a multicast address (224.0.0.1) that can address to all hosts

to send an IGMP host membership query message. If a host wants to join a multicast

group, it will reply to the multicast address of that a multicast group with an IGMP host

membership reports a message.

IGMP Snooping is also referred to as IGMP listening. The switch prevents multicast

traffic from flooding through IGMP Snooping, multicast traffic is forwarded to ports

associated to multicast devices only. The switch listens to the IGMP messages between

the multicast router and hosts, and maintains multicast group forwarding table based on

the listening result, and can then decide to forward multicast packets according to the

forwarding table.

Switch provides IGMP Snooping and is able to send a query from the switch so that

the user can use switch in IP multicast.

5.3.2

IGMP Snooping Configuration Task List

1. Enable IGMP Snooping

2. Configure IGMP Snooping